Olfactory ensheathing cells promote neurite sprouting of injured axons in vitro by direct cellular contact and secretion of soluble factors

Olfactory ensheathing cells (OECs) represent an exciting possibility for promoting axonal regeneration within the injured spinal cord. A number of studies have indicated the ability of these cells to promote significant reactive sprouting of injured axons within the injured spinal cord, and in some cases restoration of functional abilities. However, the cellular and/or molecular mechanisms OECs use to achieve this are unclear. To investigate such mechanisms, we report for the first time the ability of OECs to promote post-injury neurite sprouting in an in vitro model of axonal injury. Using this model, we were able to differentiate between the direct and indirect mechanisms underlying the ability of OECs to promote neuronal recovery from injury. We noted that OECs appeared to act as a physical substrate for the growth of post-injury neurite sprouts. We also found that while post-injury sprouting was promoted most when OECs were allowed to directly contact injured neurons, physical separation using tissue culture inserts (1 mm pore size, permeable to diffusible factors but not cells) did not completely block the promoting properties of OECs, suggesting that they also secrete soluble factors which aid post-injury neurite sprouting. Furthermore, this in vitro model allowed direct observation of the cellular interactions between OECs and sprouting neurites using live-cell-imaging techniques. In summary, we found that OECs separately promote neurite sprouting by providing a physical substrate for growth and through the expression of soluble factors. Our findings provide new insight into the ability of OECs to promote axonal regeneration, and also indicate potential targets for manipulation of these cells to enhance their restorative ability.Received 19 January 2004; received after revision 8 March 2004: accepted 17 March 2004     

Scanning electron microscopy study of spinal cord nerve cells from chick embryos cultured in vitro with poly-L-lysine]

Chick embryo nerve cells from the lumbo-sacral spinal cord have been isolated by trypsinisation and cultivated in Rose chambers on polylysine-L as a substrate. The cells are analysed by scanning electron microscopy. The mode of adherence of these cells to the substrate and the modifications of the surface of the neuroblasts during their transformation into neurocytes are studied.     

Electrophoretic study of the in vitro binding of 3,4-benzpyrene to the plasma proteins

Zusammenfassung Es wird gezeigt, dass die Verteilung von Benzpyren auf die Proteine von octanolextrahiertem Plasma einen Einblick in die bei der Plasmabindung von Substanzen vorkommenden Konkurrenzreaktionen erlaubt.     

Neuronal plasticity and regeneration in the olfactory system of mammals: morphological and functional recovery following olfactory bulb deafferentation

The mammalian olfactory system has the unique property in the permanent turnover of the olfactory sensory neurons under normal conditions and following injury. This implies that the topographical map of the epithelium-to-bulb connections generated during ontogenesis has to be maintained despite neuron renewal in order to insure olfactory information processing. One way to investigate this issue has been to disrupt the peripheral connections and analyze how neural connections may be reestablished as well as how animals may perform in olfactory-mediated tasks. This review surveys the main data pertaining to both morphological and functional recoveries taking place in the peripheral olfactory system following olfactory bulb deafferentation. Conclusions from these studies are enlightened by recent data from molecular biology.     

Production of insulin-like growth factor I (IGF-I) and IGF-binding proteins by rat intestinal stromal cells in vitro

To determine if intestinal stromal cells secrete diffusible factors such as insulin-like growth factors (IGFs) capable of regulating epithelial cell growth in vitro, stromal cells were isolated by enzymatic digestion of rat intestine. Incorporation of [³H]thymidine into DNA and [¹⁴C]leucine into protein of IEC-6 cells, a model intestinal epithelial cell line, was significantly increased (two- to threefold) when the IEC-6 cells were co-cultured with stromal cells, relative to IEC-6 cells grown alone. Medium conditioned by stromal cells stimulated DNA synthesis of IEC-6 cells in a dose-dependent manner. Analysis of the conditioned medium revealed that intestinal stromal cells secreted IGF-I, but little IGF-II, in addition to an M _r 32,000 IGF-binding protein (IGFBP-2) and an IGFBP having M _r∼ 24,000. We conclude that rat intestinal stromal cells secrete one or more diffusible factors, which may include IGF-I and IGFBPs, capable of stimulating proliferation of IEC-6 cells in vitro. Received 25 August 1997; received after revision 7 November 1997; accepted 20 November 1997     

A comparative study of nuclear proteins in chick embryo cells and their primary and secondary fibrobasts in culture

Zusammenfassung Das elektrophoretische Muster von Histonen und sauren Zellkernproteinen von Hühnerembryonen und deren primären und sekundären Fibroblastzellen wurde qualitativ und quantitativ verglichen. Die Zellkernproteine der verschiedenen Zelltypen erwiesen sich qualitativ als identisch, die relative quantitative Verteilung der Kernproteine war jedoch leicht verschieden.     

Myosin regulation in the migration of tumor cells and leukocytes within a three-dimensional collagen matrix

The migration of cells is a complex regulatory process which results in the generation of motor forces through the reorganization of the cytoskeleton. Here we present a comparative study of the expression and involvement of myosin in the regulation of the physiological migration of leukocytes and the pathological migration of tumor cells. We show that the involvement of myosin in the migration is distinct in these two cell types. In leukocytes, the activity of non-muscle myosin II is essential for both the spontaneous (matrix-induced) migration and the migration induced by ligands to G protein-coupled receptors, i.e. chemokines and neurotransmitters. In contrast, spontaneous tumor cell migration is largely independent of non-muscle myosin II activity, whereas the norepinephrine-induced migration is completely inhibited by either direct inhibition of non-muscle myosin II or of the kinases phosphorylating the myosin light chain, namely ROCK or the calcium/calmodulin-dependent myosin light-chain kinase.Received 31 August 2004; accepted 26 October 2004     

Bimodal processing of olfactory information in an amphibian nose: odor responses segregate into a medial and a lateral stream

In contrast to the single sensory surface present in teleost fishes, several spatially segregated subsystems with distinct molecular and functional characteristics define the mammalian olfactory system. However, the evolutionary steps of that transition remain unknown. Here we analyzed the olfactory system of an early diverging tetrapod, the amphibian Xenopus laevis, and report for the first time the existence of two odor-processing streams, sharply segregated in the main olfactory bulb and partially segregated in the olfactory epithelium of pre-metamorphic larvae. A lateral odor-processing stream is formed by microvillous receptor neurons and is characterized by amino acid responses and Gα_o/Gα_i as probable signal transducers, whereas a medial stream formed by ciliated receptor neurons is characterized by responses to alcohols, aldehydes, and ketones, and Gα_olf/cAMP as probable signal transducers. To reveal candidates for the olfactory receptors underlying these two streams, the spatial distribution of 12 genes from four olfactory receptor gene families was determined. Several class II and some class I odorant receptors (ORs) mimic the spatial distribution observed for the medial stream, whereas a trace amine-associated receptor closely parallels the spatial pattern of the lateral odor-processing stream. Other olfactory receptors (some class I odorant receptors and vomeronasal type 1 receptors) and odor responses (to bile acids, amines) were not lateralized, the latter not even in the olfactory bulb, suggesting an incomplete segregation. Thus, the olfactory system of X. laevis exhibits an intermediate stage of segregation and as such appears well suited to investigate the molecular driving forces behind olfactory regionalization.     

Autoradiographic study of proliferative activity and cell migration in the adrenal cortex in fetal and neonatal rats]

On the 20th day of fetal life the cell proliferation is higher in the zona glomerulosa. The fate of marked cells in each cell compartment shows centripetal migration. Their displacement, from the 20th day of pregnancy up to five days post-partum, while at that time the adrenal growth is slowered down, suggests a real migration.     

Detection of schistosomiasis in rats using micro blood sampling and immunofluorescence during an epidemiologic study]

For a study of rat parasitism with Schistosoma mansoni in Guadeloupe, we used a technique of microbloodsampling followed by an immunofluorescence test. This method makes it possible to take the blood of the rats, the latter being then marked and set loose. It informs us of the presence of the parasite, the time of infestation, and the rats' movements relative to waterspots.     

A light and electron microscope study of spherical structures in the test cells of an ascidianCiona intestinalis L.

Summary Spherical structures in the test cells that surround the embryos of the ascidianCiona intestinalis L. (Tunicata, phylum Chordata) were studied by both light and electron microscope. Our data support the view that these structures are microorganism-like cells living in symbiosis with the test cells. Their possible role is discussed.Acknowledgment. The authors are indebted to the Institute of Comparative Anatomy of Palermo for the use of the Zeiss EM 9 Electron Microscope. Particular thanks to Mr Salvatore Bucculeri for his technical assistance.     

Odor maps in the brain: Spatial aspects of odor representation in sensory surface and olfactory bulb

The olfactory sense detects and distinguishes a multitude of different odors. Recent progress in molecular as well as physiological approaches has elucidated basic principles of neuronal encoding of odorants, common to insects and vertebrates. The construction of neuronal representations for odors begins with the task of mapping the multidimensional odor space onto the two-dimensional sensory surface, and subsequently onto the olfactory bulb or antennal lobe. A distributed expression of odorant receptors, albeit restricted to subregions of the sensory surface (large, intermediate or small for zebrafish, mouse or drosophila, respectively), ensures a robust representation, insensitive to mechanical insult. Olfactory receptor neurons expressing the same odorant receptors converge to form a receptotopic map in the olfactory bulb or antennal lobe. The emerging coding principle is a chemotopic representation of odorants at the first brain level, realized either as combinatorial or as monospecific representation, depending on the odorant.     

Dynamics of proteins in Golgi membranes: comparisons between mammalian and plant cells highlighted by photobleaching techniques

In less than a decade the green fluorescent protein (GFP) has become one of the most popular tools for cell biologists for the study of dynamic processes in vivo. GFP has revolutionised the scientific approach for the study of vital organelles, such as the Golgi apparatus. As Golgi proteins can be tagged with GFP, in most cases without altering their targeting and function, it is a great substitute to conventional dyes used in the past to highlight this compartment. In this review, we cover the application of GFP and its spectral derivatives in the study of Golgi dynamics in mammalian and plant cells. In particular, we focus on the technique of selective photobleaching known as fluorescence recovery after photobleaching, which has successfully shed light on essential differences in the biology of the Golgi apparatus in mammalian and plant cells.